org.apache.felix.resolver.util.CopyOnWriteSet Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of org.eclipse.osgi Show documentation
This is org.eclipse.osgi jar used by Scout SDK
There is a newer version: 3.11.0.v20160603-1336
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.felix.resolver.util;

import java.util.AbstractSet;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;

public class CopyOnWriteSet extends AbstractSet {

    Object[] data;

    public CopyOnWriteSet() {
        data = new Object[0];
    }

    public CopyOnWriteSet(Collection col) {
        if (col instanceof CopyOnWriteSet) {
            data = ((CopyOnWriteSet) col).data;
        } else {
            data = col.toArray(new Object[col.size()]);
        }
    }

    @Override
    public Iterator iterator() {
        return new Iterator() {
            int idx = 0;
            public boolean hasNext() {
                return idx < data.length;
            }
            @SuppressWarnings("unchecked")
            public E next() {
                return (E) data[idx++];
            }
            public void remove() {
                CopyOnWriteSet.this.remove(--idx);
            }
        };
    }

    @Override
    public int size() {
        return data.length;
    }

    @Override
    public boolean add(E e) {
        Object[] d = data;
        if (d.length == 0) {
            data = new Object[] {e};
        } else {
            for (Object o : d) {
                if (o == null ? e == null : o.equals(e)) {
                    return false;
                }
            }
            Object[] a = new Object[d.length + 1];
            System.arraycopy(d, 0, a, 0, d.length);
            a[d.length] = e;
            data = a;
        }
        return true;
    }

    private void remove(int index) {
        Object[] d = data;
        int len = d.length;
        Object[] a = new Object[len - 1];
        int numMoved = len - index - 1;
        if (index > 0) {
            System.arraycopy(d, 0, a, 0, index);
        }
        if (numMoved > 0) {
            System.arraycopy(d, index + 1, a, index, numMoved);
        }
        data = a;
    }

    @Override
    public boolean equals(Object o) {
        if (o instanceof CopyOnWriteSet && ((CopyOnWriteSet) o).data == data) {
            return true;
        }
        return super.equals(o);
    }

    @Override
    public int hashCode() {
        return Arrays.hashCode(data);
    }

}